PHP根据URL提取根域名，个人工作中用到，由于网络上很多代码都不能得到正确结果就自己写了一个，欢迎大家使用并提出其中的bug.
<?php #使用示例echo getBaseDomain("http://blog.jp.goo.ne.jp/index.php")->domain;echo "";echo getBaseDomain("http://51.ca/index.php")->domain;echo "";echo getBaseDomain("http://blog.ab.cc.win.aisa.hk/index.php")->domain;echo ""; function getBaseDomain($url=""){ if(!$url){ return $url; } #列举域名中固定元素 $state_domain = array( "al","dz","af","ar","ae","aw","om","az","eg","et","ie","ee","ad","ao","ai","ag","at","au","mo","bb","pg","bs","pk","py","ps","bh","pa","br","by","bm","bg","mp","bj","be","is","pr","ba","pl","bo","bz","bw","bt","bf","bi","bv","kp","gq","dk","de","tl","tp","tg","dm","do","ru","ec","er","fr","fo","pf","gf","tf","va","ph","fj","fi","cv","fk","gm","cg","cd","co","cr","gg","gd","gl","ge","cu","gp","gu","gy","kz","ht","kr","nl","an","hm","hn","ki","dj","kg","gn","gw","ca","gh","ga","kh","cz","zw","cm","qa","ky","km","ci","kw","cc","hr","ke","ck","lv","ls","la","lb","lt","lr","ly","li","re","lu","rw","ro","mg","im","mv","mt","mw","my","ml","mk","mh","mq","yt","mu","mr","us","um","as","vi","mn","ms","bd","pe","fm","mm","md","ma","mc","mz","mx","nr","np","ni","ne","ng","nu","no","nf","na","za","aq","gs","eu","pw","pn","pt","jp","se","ch","sv","ws","yu","sl","sn","cy","sc","sa","cx","st","sh","kn","lc","sm","pm","vc","lk","sk","si","sj","sz","sd","sr","sb","so","tj","tw","th","tz","to","tc","tt","tn","tv","tr","tm","tk","wf","vu","gt","ve","bn","ug","ua","uy","uz","es","eh","gr","hk","sg","nc","nz","hu","sy","jm","am","ac","ye","iq","ir","il","it","in","id","uk","vg","io","jo","vn","zm","je","td","gi","cl","cf","cn","yr","com","arpa","edu","gov","int","mil","net","org","biz","info","pro","name","museum","coop","aero","xxx","idv","me","mobi","asia","ax","bl","bq","cat","cw","gb","jobs","mf","rs","su","sx","tel","travel" ); if(!preg_match("/^http/is", $url)){ $url="http://".$url; } $res = null; $res->domain = null; $res->host = null; $url_parse = parse_url(strtolower($url)); $urlarr = explode(".", $url_parse["host"]); $count = count($urlarr); if($count <= 2){ #当域名直接根形式不存在host部分直接输出 $res->domain = $url_parse["host"]; }elseif($count > 2){ $last = array_pop($urlarr); $last_1 = array_pop($urlarr); $last_2 = array_pop($urlarr); $res->domain = $last_1.".".$last; $res->host = $last_2; if(in_array($last, $state_domain)){ $res->domain=$last_1.".".$last; $res->host=implode(".", $urlarr); } if(in_array($last_1, $state_domain)){ $res->domain = $last_2.".".$last_1.".".$last; $res->host = implode(".", $urlarr); } #print_r(get_defined_vars());die; } return $res; } 